1. Technical Field
The present invention generally relates to a broadband surge suppression module having an optical coupling channel and, more particularly, to a broadband surge suppression module having an optical coupling channel, which can suppress high-power surges flowing into a control system through a digital signal line of the control system, which requires the connection of a conductive line, using an optical coupling channel.
2. Description of the Related Art
In control systems for electrical and industrial facilities, the connection of a large number of lines to transfer various control signals is required. For example, in the case of power network control systems, the connection of power lines for system operation, signal lines required to monitor the status of power control equipment, such as a power circuit breaker or a disconnecting switch, and control lines required to transmit/receive control signals is required. Depending on the function or type of equipment, a large number of signal lines/control lines may be used. As all lines connected to a control system, conductive transmission lines are used for the delivery of power and signals. Such a line may function as a path for transferring an external high-power surge to the inside of the control system.
When the strength of a surge transferred into the control system is higher than the withstand voltage of an internal electronic circuit, the malfunctioning or physical breakdown of the control system may occur, and thus surge suppression devices (or surge protection devices) suitable for the characteristics of respective lines must be added in order to protect the system against a conductive surge.
Generally, a surge suppression device for conductive paths is called a filter, and the basic function thereof is the function of a frequency selector for removing unwanted frequency components from a signal transferred through a line. A filter is a circuit that combines an inductor and a capacitor, and is categorized as a low-pass filter or a high-pass filter depending on which frequencies pass through the filter. In a filter for suppressing high-power surges, a filter circuit and a separate surge protection device (SPD) may occasionally be installed together. The SPD connected to the inside or input terminal of the filter circuit induces a high-power surge signal to flow through a ground line when the high-power surge signal is applied, thus preventing the surge signal from being applied to the input terminal of the filter circuit.
The rated specification of the inductor and the capacitor constituting a filter circuit is determined by the strengths of signals applied to the line. Since a part having a large volume and a high rated value must be used to manufacture a filter capable of accommodating a high rated value, the volume of the manufactured filter increases. In particular, due to the use of an inductor, in which an iron core is used, the volume of the filter inevitably increases according to the rated specification, thus imposing a limitation on manufacture at a small size. In particular, in a high-power surge suppression filter, a separate high-power surge protection device is installed together with a filter circuit, and thus there is a disadvantage with regard to the implementation of a filter having a small volume.
In order to protect the control system against high-power electromagnetic interference, the system to be protected must be installed in an electromagnetically shielded space, and transmission lines to be connected to the corresponding system are installed to penetrate through an electromagnetic shielding wall. Generally, conductive lines connected to a system installed in an electromagnetically shielded space are connected to the inside of the electromagnetically shielded space through a suitable filter, and a high-power surge suppression filter is installed such that it is electrically connected to the electromagnetic shielding wall.
For example, when the corresponding system is installed in an electromagnetically shielded space to protect a power network control system, multiple lines must be installed such that they penetrate through the electromagnetic shielding wall. The power network control system requires the connection of power lines, signal lines, and control lines, and also requires the connection of several tens or more of signal lines and control lines for respective pieces of equipment. In this way, to install filters for the connection of a large number of lines, a very large space is required for the installation of the filters.
When multiple filters are installed on a shielding wall, the electromagnetic shielding performance of the shielding wall may be deteriorated due to the formation of multiple holes through the shielding wall, and moreover, the prices of commercial filter products are as high as several hundreds Dollars or more, thus adding to the expense of the control system.
In relation to this, Korean Patent Application Publication No. 2005-0029078 discloses technology entitled “Surge Cancel Apparatus”.